How fast does your R400 go?

[akb]

I have not managed to read-line my R400D on the track but at 6000 rpm in sixth it is doing 105mph so at 7600 read line that would imply 134mph. Caterham claim 140mph. What have other folks seen? Would the difference by 13in vs 15in wheels or perhaps I have a strange diff ratio. The difference does not seem to be enough to be the diff ratio.

 

Andy

[MADMALC]

I have an RPM MPH calculator that may be of help.

My SLR on ACB10's will be doing 144mph at 8000rpm in 6th gear.

Blatmail me and I will send it to you. You just put your details in and it gives the answer.

 

S7MAD

[Shad]

GearCalc is what you want. It even has the ratios for the Caterham 6 speed box preset

 

Simon

niknak.org

[Mankee]

There is also a handy gear calculator on the gearboxman website here.

[6speedmanual]

Hi Andy

 

From the speed/revs stated, you do have a 3.62:1 diff in there as it should be.

 

My original R400 K series has the benefit of a greater rev range. It would theoretically do 140mph at 8000rpm. If your R400 D(iesel)? is redlined at 7600 it won't do 140mph unless the real rev limit is higher?

 

The best I've seen is 7800 in 6th but ran out of road. T'was at the 'Ring final straight but had to back off as the car park barrier exit hoved into view. Passed the 130Km/h lollipop at 130mph ! 😳

 

K pretty nifty on standing starts too with a 12.41 sec at 110.89mph Qtr mile a FCITW'09

 

😬

 

Peter

 

BRAWNGP green SUPERLIGHT

FCITW 2009 😬

[Grubbster]

My K series Roadsport with a 5 speed box would exceed 180mph on the rev limiter in 5th if it could get there 😬

 

Solent Se7ens Web!

[john aston]

My R400 would do 500mph plus - in second - according to the oh so accurate Stack.Now it's fixed I haven't been over 126 mph in sixth.On my private test track .

[Steve Campbell]

Haven't tried it yet as the track day I went to on Saturday was very very very wet ! Incidentally, can someone confirm what the R400D redline should be set at ? I just bought the change up lights on the bulk buy and was wondering what I should be setting the red light to come on at ??

 

Steve Campbell

Orange R400 Duratec

[rj]

Depends on tyres. Mine, which is not an R, hits the rev limiter in 6th at 208-218km/h (129-134MPH) subject to rear tyres diameter.

 

Rev limiter set to 7k8

[charlie_pank]

I think unless you improve aerodynamics, anything over 130 is very good (or your speedo's over reading)

 

back here because I want to be.

[Shad]

You could always switch to a 3.92 final drive. My little 140hp K has no trouble hitting the limiter in 6th on the flat, works out to 124mph I believe 😬

 

Simon

niknak.org

[EFA]

I think unless you improve aerodynamics, anything over 130 is very good (or your speedo's over reading)

---

 

Aero becomes more of a problem over about 150mph where the front of the car starts to get very light such that keeping things straight on a 30m wide runway becomes an issue. Not that you would achive this in an R400 of course.

 

140mph is where you need serious power to overcome the drag.

[Pat the Plumber]

137mph on the rev limiter, with a windscreen, on the track ofcourse.

the standard R400 used to have 15" so presume that the difference is 3mph top end, but losing out on acceleration/

 

my R400

[akb]

Thanks for all the links to gearcalc and helpful comments. So it seems that 135 ish is the limit for a R400 D with 13in wheels.

 

The rev limit is 7600. The aerodynamics do not seem to be an issue with an aeroscreen and is still pulling very strong at 120 mph+. If anything the gearing feels a little low.

 

Good luck, all.